The mechanism of gene regulation at the molecular level is being studied with special emphasis on the role of DNA properties as a determinant of specificity. One objective of this project is to identify and characterize the dynamic structure of procaryotic double-stranded DNA's, with the goal of determining the correlation between DNA physical and biological determinations will be performed on DNA's with established sequences, including procaryotic viral DNA's, highly purified DNA restriction fragments containing known genetic loci, mutant DNA's with known phenotypes and sequence changes, and DNA model polymers. The DNA restriction fragments will be purified by high pressure RPC-5 column chromatography and/or by gene cloning. Studies will be concentrated on regulatory sites containing operators and promoters with established nucleotide sequences. An understanding of the details of gene expression is fundamental to our ultimate comprehension of normal cellular growth and division, as well as disease syndromes characterized by unregulated growth, such as cancer.